Dropout from exercise trials among cancer survivors—An individual patient data meta-analysis from the POLARIS study

Introduction: The number of randomized controlled trials (RCTs) investigating the effects of exercise among cancer survivors has increased in recent years; however, participants dropping out of the trials are rarely described. The objective of the present study was to assess which combinations of participant and exercise program characteristics were associated with dropout from the exercise arms of RCTs among cancer survivors. Methods: This study used data collected in the Predicting OptimaL cAncer RehabIlitation and Supportive care (POLARIS) study, an international database of RCTs investigating the effects of exercise among cancer survivors. Thirty-four exercise trials, with a total of 2467 patients without metastatic disease randomized to an exercise arm were included. Harmonized studies included a pre and a posttest, and participants were classified as dropouts when missing all assessments at the post-intervention test. Subgroups were identified with a conditional inference tree. Results: Overall, 9.6% of the participants dropped out. Five subgroups were identified in the conditional inference tree based on four significant associations with dropout. Most dropout was observed for participants with BMI &gt;28.4 kg/m2, performing supervised resistance or unsupervised mixed exercise (19.8% dropout) or had low-medium education and performed aerobic or supervised mixed exercise (13.5%). The lowest dropout was found for participants with BMI &gt;28.4 kg/m2 and high education performing aerobic or supervised mixed exercise (5.1%), and participants with BMI ≤28.4 kg/m2 exercising during (5.2%) or post (9.5%) treatment. Conclusions: There are several systematic differences between cancer survivors completing and dropping out from exercise trials, possibly affecting the external validity of exercise effects.</p

Dropout from exercise trials among cancer survivors-An individual patient data meta-analysis from the POLARIS study

INTRODUCTION: The number of randomized controlled trials (RCTs) investigating the effects of exercise among cancer survivors has increased in recent years; however, participants dropping out of the trials are rarely described. The objective of the present study was to assess which combinations of participant and exercise program characteristics were associated with dropout from the exercise arms of RCTs among cancer survivors. METHODS: This study used data collected in the Predicting OptimaL cAncer RehabIlitation and Supportive care (POLARIS) study, an international database of RCTs investigating the effects of exercise among cancer survivors. Thirty-four exercise trials, with a total of 2467 patients without metastatic disease randomized to an exercise arm were included. Harmonized studies included a pre and a posttest, and participants were classified as dropouts when missing all assessments at the post-intervention test. Subgroups were identified with a conditional inference tree. RESULTS: Overall, 9.6% of the participants dropped out. Five subgroups were identified in the conditional inference tree based on four significant associations with dropout. Most dropout was observed for participants with BMI >28.4 kg/m 2 , performing supervised resistance or unsupervised mixed exercise (19.8% dropout) or had low-medium education and performed aerobic or supervised mixed exercise (13.5%). The lowest dropout was found for participants with BMI >28.4 kg/m 2 and high education performing aerobic or supervised mixed exercise (5.1%), and participants with BMI ≤28.4 kg/m 2 exercising during (5.2%) or post (9.5%) treatment. CONCLUSIONS: There are several systematic differences between cancer survivors completing and dropping out from exercise trials, possibly affecting the external validity of exercise effects

Effects and moderators of exercise on quality of life and physical function in patients with cancer:An individual patient data meta-analysis of 34 RCTs

This individual patient data meta-analysis aimed to evaluate the effects of exercise on quality of life (QoL) and physical function (PF) in patients with cancer, and to identify moderator effects of demographic (age, sex, marital status, education), clinical (body mass index, cancer type, presence of metastasis), intervention-related (intervention timing, delivery mode and duration, and type of control group), and exercise-related (exercise frequency, intensity, type, time) characteristics. Relevant published and unpublished studies were identified in September 2012 via PubMed, EMBASE, PsycINFO, and CINAHL, reference checking and personal communications. Principle investigators of all 69 eligible trials were requested to share IPD from their study. IPD from 34 randomised controlled trials (n=4,519 patients) that evaluated the effects of exercise compared to a usual care, wait-list or attention control group on QoL and PF in adult patients with cancer were retrieved and pooled. Linear mixed-effect models were used to evaluate the effects of the exercise on post-intervention outcome values (z-score) adjusting for baseline values. Moderator effects were studies by testing interactions. Exercise significantly improved QoL (β=0.15, 95%CI=0.10;0.20) and PF (β=0.18,95%CI=0.13;0.23). The effects were not moderated by demographic, clinical or exercise characteristics. Effects on QoL (βdifference_in_effect=0.13, 95%CI=0.03;0.22) and PF (βdifference_in_effect=0.10, 95%CI=0.01;0.20) were significantly larger for supervised than unsupervised interventions. In conclusion, exercise, and particularly supervised exercise, effectively improves QoL and PF in patients with cancer with different demographic and clinical characteristics during and following treatment. Although effect sizes are small, there is consistent empirical evidence to support implementation of exercise as part of cancer care

Psychological, social and physical environmental mediators of the SCORES intervention on physical activity among children living in low-income communities

Objectives: This study examined mediation effects of socio-ecological variables on accelerometer determined physical activity among children in the Supporting Children's Outcomes using Rewards, Exercise and Skills (SCORES) intervention. Design: Randomized control trial mediation analysis. Methods: Primary school children were randomly assigned the SCORES multi-component intervention or control group for the 12-month study. The outcome was accelerometer derived total moderate-to vigorous physical activity (MVPA). Hypothesized mediators measured in children were physical activity enjoyment and perceived sport competence and social support. Hypothesized mediators measured in parents were family social support, access to physical activity facilities and equipment at home, and perceived access to physical activity opportunities in the local community. Mediation analyses were conducted using multi-level linear analysis in MPlus. Results: There were significant intervention effects for social support from teachers (A ¼ 1.73, SE ¼ 0.88, p ¼ 0.048) and parental perceived access to physical opportunities in the local community (A ¼ 2.69, SE ¼ 1.12, p ¼ 0.016). There were significant associations between changes in perceived sport competence (B ¼ 0.48, SE ¼ 0.36, p ¼ 0.027), parental perceived access to physical activity opportunities in the local community (B ¼ 0.60, SE ¼ 0.26, p ¼ 0.021), and changes in total MVPA. Parental perceived access to physical activity opportunities in the local community was found to have a significant mediating effect on total MVPA (AB ¼ 1.61, 95% CI ¼ 0.06 to 3.95, proportion 13%). Conclusions: Parental perceived access to physical activity opportunities in the local community is a potential mechanism of behavior change for children and mediated the effect of the SCORES intervention on objectively measured physical activit

Mediators of change in screen-time in a school-based intervention for adolescent boys: findings from the ATLAS cluster randomized controlled trial

The mechanisms of behavior change in youth screen-time interventions are poorly understood. Participants were 361 adolescent boys (12–14 years) participating in the ATLAS obesity prevention trial, evaluated in 14 schools in low-income areas of New South Wales, Australia. Recreational screen-time was assessed at baseline, 8- and 18-months, whereas potential mediators (i.e., motivation to limit screen-time and parental rules) were assessed at baseline, 4- and 18-months. Multi-level mediation analyses followed the intention-to-treat principle and were conducted using a product-of-coefficients test. The intervention had a significant impact on screen-time at both time-points, and on autonomous motivation at 18-months. Changes in autonomous motivation partially mediated the effect on screen-time at 18-months in single and multimediator models [AB (95% CI) = -5.49 (-12.13, -.70)]. Enhancing autonomous motivation may be effective for limiting screen-time among adolescent males. Trial registration: Australian New Zealand Clinical Trials Registry No: ACTRN12612000978864

Intervention to reduce recreational screen-time in adolescents: outcomes and mediators from the 'Switch-off 4 healthy minds' (S4HM) cluster randomized controlled trial

Introduction: Excessive recreational screen-time in adolescents is a public health problem in westernised countries, with little research conducted among adolescents. The primary objective of this study was to evaluate the impact of the ‘Switch-off 4 Healthy Minds’ (S4HM) intervention designed to reduce recreational screen-time in adolescents. Methods: A cluster randomized controlled trial with 6-month follow-up was conducted. Eight secondary schools in the Hunter region of New South Wales, Australia, were recruited. The S4HM intervention was guided by self-determination theory and included: an interactive seminar, eHealth messaging using social media, behavioral contract and parental newsletters. Participants (treatment n = 167, control n = 155) were adolescent males (34.5%) and females (65.5%) in grade 7 (Mean age = 14.4 ± 0.6 years), who reported exceeding recreational screen-time recommendations (i.e., > 2 h/day). The primary outcome was self-reported recreational screen-time measured at baseline and post-test (6-months). Secondary outcomes were mental health outcomes, objectively measured physical activity, and body mass index (BMI). Mediation analyses were conducted to determine if changes in motivation mediated the intervention effect. Results: Significant reductions in screen-time were observed in both groups from baseline to post-test (−51.2 min/day, p < 0.001 in the intervention group, −34.5 min/day, p = 0.021 in the control group, however the between group difference of −16.7 min/day was not statistically significant, p = 0.422). There were no significant intervention effects for any of the mental health outcomes, objectively measured physical activity or BMI. In both single and multiple mediator models, the intervention effect was partially mediated by increases in autonomous motivation to limit screen-time. Discussion: There was no intervention effect, as both the intervention and control groups reduced their screen-time over the study period. However, findings highlight the challenges of working to reduce screen-time among adolescents and highlight an urgent need to identify strategies to reduce screen-time based on the (83%) of 1107 students screened and exceeded screen-time guidelines. The non-significant intervention effects on screen-time were mediated by increases in autonomous motivation to limit recreational screen-time. As autonomous but not controlled motivation mediated such an effect, findings suggest a need to deal with intrinsic motivation which people integrate a value of an activity into their sense of self. This is a notable finding and highlights the potential for using SDT as a theoretical framework for screen-time reduction in adolescent populations

Erratum to: Scaling-up an efficacious school-based physical activity intervention: Study protocol for the ‘Internet-based Professional Learning to help teachers support Activity in Youth’ (iPLAY) cluster randomized controlled trial and scale-up implementation evaluation

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